Thorax:Hollow viscus:Oesophagus
The oesophagus is a muscular tube that conveys food and fluids from the oropharynx to the stomach. The oesophagus is 25 cm long with a diameter of 1-2 cm and is divided into three parts: * cervical: continuous with the oropharynx, commences at the lower border of cricoid cartilage (at level of C5/6) or cricopharyngeus muscle, in front of the prevertebral fascia * thoracic: from thoracic aperture (T1) to the oesophageal hiatus (T11) * abdominal: from oesophageal hiatus and is continuous with the cardia of the stomach at the gastro-oesophageal junction It courses inferiorly to the left of the midline in the neck, enters the thoracic inlet to the superior mediastinum. At level of T5, it returning to the midline before coursing to the left again of the midline in the posterior mediastinum. At its inferior aspect, the oesophagus curves anteriorly to pass through the diaphragm via the oesophageal opening into the abdominal cavity. There are three normal oesophageal constrictions that should not be confused for pathological constrictions: * cervical constriction: due to cricopharyngeus at the level of C5/6 * thoracic constriction: due to aortic arch at the level of T4/5 and left main bronchus * abdominal constriction: at oesophageal hiatus at T10/11 Musculature * Has internal circular and external longitudinal layers of muscle * Superior third of esophagus consists of voluntary, striated muscle; lower ¹/₃ = smooth muscle; middle ¹/₃ = both types Sphincters * Upper esophageal sphincter ** At pharyngoesophageal junction ** Formed primarily by cricopharyngeus muscle * Lower esophageal sphincter ** Region of high resting tone or pressure Relations * posteriorly: vertebral column; descending aorta; thoracic duct (at thoracic plane); accessory hemiazygos and hemiazygos veins (at T8/9) * anteriorly: trachea (to T4/5); recurrent laryngeal nerves (in tracheo-oesophageal groove); left main bronchus; left atrium * left lateral: lung; pleura; descending aorta; left subclavian artery; thoracic duct * right lateral: lung; pleura; azygos vein Blood supply * arterial supply ** upper third: inferior thyroid artery ** middle third: oesophageal branches of the thoracic aorta ** lower third: oesophageal branches of the left gastric artery (site of portal-systemic collateral pathway) * venous drainage ** upper third: inferior thyroid veins to brachiocephalic veins ** middle third: azygos vein to SVC ** lower third: left gastric vein to portal vein Nerve supply * sympathetic trunk (sympathetic fibres) * right and left vagal plexus (parasympathetic fibres) Lymphatic drainage: follows arterial supply * upper third: deep cervical lymph nodes * middle third: posterior mediastinal lymph nodes * lower third: left gastric and coeliac group lymph nodes Variant anatomy * oesophageal bronchus * oesophageal atresia * aberrant right subclavian artery passing anterior or posterior to the oesophagus Cervical esophagus * Begins at lower border of cricoid cartilage as continuation of hypopharynx ** Upper limit is defined by cricopharyngeus muscle, which encircles it from front to back * Blood supply: Inferior thyroid arteries & veins * Lymphatic drainage: Level VI paratracheal nodes * Relation: ** Anterior structure: Cervical trachea ** Anterolateral structures: Tracheoesophageal groove structures ** Lateral structures: Carotid spaces ** Posterior structures: Retropharyngeal/danger spaces